Baseninduzierte umlagerung tertiärer dichlormethyl-alkoxylate in α-Chlorketon-enolate

Reactivity of Oxiranes with Organolithium Reagents

“…These reactions, attributed to a β-oxido carbenoid intermediate, could also be attributed to an α-halogeno lithiooxirane, which could then undergo alkyl migration (and not intermolecular insertion into a C−Li bond as in Scheme 89) to give the lithium enolate observed at the end of the reaction. This alternative mechanistic hypothesis had been proposed 332,333 in the early work on this one-carbon homologation reaction. …”

New, General, and Stereoselective Synthesis of CF3-Containing Tri- and Tetrasubstituted Oxiranes and Tetrasubstituted Alkenes

“…Treatment of PhMeC(OLi)CHCl 2 or Ph 2 C(OH)CHCl 2 with excess BuLi or PhLi was reported to produce respectively MeCOCH(Cl)Ph or Ph 2 CHCOPh in ref f. It is not clear why no rearrangement took place in 1 .…”

“…It is well-established that the rearrangement of β-oxido carbenoids generated from dihalohydrins is useful for homologation of aldehydes as well as acyclic and cyclic ketones, while there is no precedent regarding CF 3 -substituted β-oxido carbenoids. We became interested in the carbenoids in view of novel synthesis of CF 3 -containing organic molecules that are receiving much attention in pharmaceutical and material sciences …”

Dichloromethyllithium: Synthesis and Application in Continuous Flow Mode

“…Various examples in the literature demonstrate the synthetic usefulness of dichloromethyllithium (DCMLi) as an organometallic intermediate in organic chemistry . Addition of DCMLi to carbonyl compounds provides β,β-dichloromethyl carbinols, which represent useful building blocks for further functionalization toward entities such as epoxides, O , O -acetals, aldehydes, styrenes, α,α-dichloromethyl ketones, terminal alkynes, and many heterocyclic compounds. , In addition, among many other transformations, DCMLi allows the direct chain homologation of arylboronic esters, giving access to valuable benzylic (α-chloro) boronic esters, a substrate class of enormous synthetic value …”

“…Although the broad applicability of DCMLi is well reported in the literature, its usage, especially on a larger scale, is limited due to the labile nature of the metallic species. The generation of dichloromethyllithium from dichloromethane and n BuLi or lithium amine bases (e.g., LiHMDS, LDA) in traditional batch mode requires very low cryogenic temperatures (IT = −78 to −100 °C) to suppress the formation of a carbene species and consecutive degradation pathways. − , Consequently, the utilization of DCMLi in batch mode is restricted to either small-scale applications or requires specialized (expensive) low-temperature equipment.…”